I received a book today that I requested but I can't mark it received because the sender didn't mark it mailed.  What should I do?

Is it still on your requested tab? If so then you need to PM the sender to get them to mark it mailed.

If it has timed out and is not in your requested tab, then you need to go to your Transaction Archive and mark it received from there.

Make sure you compare the sender to what the system says so you mark the correct on as received. If it was a WL book and it timed out in the system, make sure to go remove it from your WL.

If you search the Help Center by what you titled this post, you should find the detailed instructions.

Melanie, I thought that if the sender didn't mark it mailed it wouldn't show up on the TA?

It shows up in your transaction archive with a big red X.  I had one recently and just checked.  I think if you request a book and they never accept then it doesn't show up. But if it's been accepted and then not marked mailed or cancelled for some reason it does. 

Definately make sure the book came from the person in the TA before you mark it received.  If there were other copies posted the system will automatically reorder the book from you. But you would see it in your enroute to me tab.  If it arrived fast and hasn't timed out-then send them a PM.  But keep an eye on it: if they still don't respond you need to cancel the next request before it gets printed.  Then you can mark this one received from the transaction archive.